RESUMO
Mutations in the genes encoding nuclear factor (erythroid-derived 2)-like 2 (NRF2), Kelch-like ECH-associated protein 1 (KEAP1), and cullin 3 (CUL3) are commonly observed in human esophageal squamous cell carcinoma (ESCC) and result in activation of the NRF2 signaling pathway. Moreover, hyperactivity of the transcription factor Nrf2 has been found to cause esophageal hyperproliferation and hyperkeratosis in mice. However, the underlying mechanism is unclear. In this study, we aimed to understand the molecular mechanisms of esophageal hyperproliferation in mice due to hyperactive Nrf2. Esophageal tissues were obtained from genetically modified mice that differed in the status of the Nrf2 gene and genes in the same pathway (Nrf2-/-, Keap1-/-, K5Cre;Pkm2fl/fl;Keap1-/-, and WT) and analyzed for metabolomic profiles, Nrf2 ChIP-seq, and gene expression. We found that hyperactive Nrf2 causes metabolic reprogramming and up-regulation of metabolic genes in the mouse esophagus. One of the glycolysis genes encoding pyruvate kinase M2 (Pkm2) was not only differentially up-regulated, but also glycosylated and oligomerized, resulting in increased ATP biosynthesis. However, constitutive knockout of Pkm2 failed to inhibit this esophageal phenotype in vivo, and this failure may have been due to compensation by Pkm1 up-regulation. Transient inhibition of NRF2 or glycolysis inhibited the growth of human ESCC cells in which NRF2 is hyperactive in vitro In summary, hyperactive Nrf2 causes metabolic reprogramming in the mouse esophagus through its transcriptional regulation of metabolic genes. Blocking glycolysis transiently inhibits cell proliferation and may therefore have therapeutically beneficial effects on NRF2high ESCC in humans.
Assuntos
Reprogramação Celular , Esôfago/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Transcrição Gênica , Trifosfato de Adenosina/genética , Trifosfato de Adenosina/metabolismo , Animais , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patologia , Linhagem Celular , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/metabolismo , Neoplasias Esofágicas/patologia , Esôfago/patologia , Glicólise , Células-Tronco Embrionárias Humanas/metabolismo , Células-Tronco Embrionárias Humanas/patologia , Humanos , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Camundongos , Camundongos Knockout , Fator 2 Relacionado a NF-E2/genética , Piruvato Quinase/genética , Piruvato Quinase/metabolismoRESUMO
Esophageal squamous cell carcinoma (ESCC) is a deadly disease that requires extensive research. Here, we review the current understanding of the functions of the nuclear factor erythroid-derived 2-like 2 (NRF2) signaling pathway in the esophagus. Genomic data suggest that gene mutations and several other mechanisms result in NRF2 hyperactivation in human ESCC. As a consequence, NRF2high ESCC is more resistant to chemoradiotherapy and associated with poorer survival than NRF2low ESCC. Mechanistically, we believe NRF2, functioning as a transcription factor, causes an esophageal phenotype through regulation of gene transcription. We discuss metabolism, mitochondria, proteasomes, and several signaling pathways as downstream players that may contribute to an esophageal phenotype due to NRF2 hyperactivation. Finally, strategies are proposed to target the NRF2 signaling pathway for therapy of NRF2high ESCC.
Assuntos
Neoplasias Esofágicas , Carcinoma de Células Escamosas do Esôfago , Esôfago , Regulação Neoplásica da Expressão Gênica , Fator 2 Relacionado a NF-E2 , Proteínas de Neoplasias , Transdução de Sinais , Animais , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/metabolismo , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/terapia , Carcinoma de Células Escamosas do Esôfago/genética , Carcinoma de Células Escamosas do Esôfago/metabolismo , Carcinoma de Células Escamosas do Esôfago/patologia , Carcinoma de Células Escamosas do Esôfago/terapia , Esôfago/metabolismo , Esôfago/patologia , Humanos , Fator 2 Relacionado a NF-E2/biossíntese , Fator 2 Relacionado a NF-E2/genética , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genéticaRESUMO
Oxidative stress is known to play a pivotal role in the development of oral squamous cell carcinoma (OSCC). We have demonstrated that activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway has chemopreventive effects against oxidative stress-associated OSCC. However, Nrf2 have dual roles in cancer development; while it prevents carcinogenesis of normal cells, hyperactive Nrf2 also promotes the survival of cancer cells. This study is aimed to understand the function of Nrf2 in regulating cellular behaviors of OSCC cells, and the potential mechanisms through which Nrf2 facilitates OSCC. We established the Nrf2-overexpressing and Nrf2-knockdown OSCC cell lines, and examined the function of Nrf2 in regulating cell proliferation, migration, invasion, cell cycle and colony formation. Our data showed that Nrf2 overexpression promoted cancer phenotypes in OSCC cells, whereas Nrf2 silencing inhibited these phenotypes. In addition, Nrf2 positively regulated Notch signaling pathway in OSCC cells in vitro. Consistent with this observation, Nrf2 activation in Keap1-/- mice resulted in not only hyperproliferation of squamous epithelial cells in mouse tongue as evidenced by increased expression of PCNA, but also activation of Notch signaling in these cells as evidenced by increased expression of NICD1 and Hes1. In conclusion, Nrf2 regulates cancer behaviors and Notch signaling in OSCC cells.
